New York swimmer swept out to sea treaded water for five hours and made flag from fishing pole before rescue

It was a stroke of unbelievable good luck. After treading water for hours, Dan Ho spotted a friendly boat heading towards him.

The 63-year-old, from Copiague, New York, was swept out to sea early Monday morning in the waters off Cedar Beach, Long Island, in a strong current that took him an estimated 2.5 miles away from the shore.

After treading for hours in the cold, he found a floating fishing road and tied his shirt to it, making a makeshift flag that caught the attention of Jim Hohorst and Michael Ross, a pair of civilians boating off Long Island around 10.30am.

The mariners hauled up Mr Ho, wrapped him in towels, and called the police, who transported the 63-year-old to a US Coast Guard station on Fire Island.

"He was just treading water, praying some boat would come by," Mr Ross told ABC 7 NY. "I can tell you, no boats in the area, not for miles."

"He was blue, (his) body gray," he added. "He was shaking, totally hyperthermic. (We) wrapped him in towels."

Mr Ho was conscious and alert when police encountered him, but unable to stand from exhaustion. He was taken to Good Samaritan University Hospital in West Islip, according to officials.

Strong currents were responsible for a string of deaths during June.

Eleven people have died over the last two weeks of the month along the Gulf Coast due to dangerous rip currents, according to data from the National Weather Service.

“Rip currents are powerful, channeled currents of water flowing away from shore,” according to the National Oceanic and Atmospheric Administration. “They typically extend from the shoreline, through the surf zone, and past the line of breaking waves.”

The currents prove especially lethal because people often try to swim against the direction of the moving water to get to safety, which can tire out even the most powerful swimmers. Instead, experts advise those caught in rip currents to swim sideways or at an angle away from the outflowing current, parallel to the beach, until they are outside of its pull and can get to safety.

Swimmers are always advised to check local conditions and heed warnings from lifeguards and other ocean experts before ocean swimming.